Adaptive array processing (hereinafter, AAS processing) performed by a so-called adaptive antenna system (AAS) has been known (for example, Patent Document 1). The AAS processing is performed to find a weighting factor to be used for providing directivity to a desired wave by suppressing delay waves and interference waves, in an OFDM radio transmission/reception device.
In the AAS processing, when the OFDM radio transmission/reception device receives a radio signal, a diversity gain by multiple antennas is obtained only for a desired signal by suppressing delay waves and interference waves.
When the OFDM radio transmission/reception device transmits a radio signal, a radio signal generated by adding gains corresponding to the number of the antennas and a beamforming gain is transmitted to a desired terminal. Accordingly, reception of interference waves by a terminal other than the desired terminal can be suppressed.
However, in the OFDM, when adjacent sub-carriers are not orthogonal to each other, errors in the decoding of received signals increase. For this reason, channel estimation for each sub-carrier is required in the OFDM.
The radio communication device described in Patent Document 1 performs AAS processing in OFDM after channel estimation to optimize a direct wave or a delay wave received at a high reception level among received signals.
Patent Document 1: Japanese Patent Application Publication No. 2003-264526